Quick answer
年末調整 (nenmatsu chōsei, year-end adjustment) is the income tax settlement that your company (employer) does for you at year-end: it compares the total income tax withheld at source (源泉徴収, gensen chōshū) from your monthly salary over the year against the income tax you actually owe for that year, and refunds or collects the difference. Your main job is to fill in and submit a few 申告書 (shinkokusho, declaration forms) as your company instructs; the settlement result shows up on the 源泉徴収票 (gensen chōshū-hyō, withholding tax statement) you receive at year-end. For most employees this completes the process — no separate 確定申告 (kakutei shinkoku, final tax return) is needed; but you still file your own return in cases such as the medical expense deduction (医療費控除, iryōhi kōjo), side-job or other income reaching the filing threshold, or the first year of the home loan deduction (thresholds below; follow the National Tax Agency).
What this document is
「年末調整」 is not a single document but a procedure your company carries out at year-end. To complete it, employees typically submit the following 申告書 (declaration forms) — exact names follow what your company hands out and the National Tax Agency's official formats:
- 給与所得者の扶養控除等（異動）申告書 (kyūyo shotokusha no fuyō kōjo tō (idō) shinkokusho) — declares your dependents and similar information; the basis for applying the various deductions (generally submitted to your main employer).
- 給与所得者の保険料控除申告書 (kyūyo shotokusha no hokenryō kōjo shinkokusho) — declares insurance premium deductions such as life/medical insurance and social insurance.
- 基礎控除申告書 兼 配偶者控除等申告書 兼 特定親族特別控除申告書 兼 所得金額調整控除申告書 (kiso kōjo shinkokusho ken haigūsha kōjo tō shinkokusho ken tokutei shinzoku tokubetsu kōjo shinkokusho ken shotoku kingaku chōsei kōjo shinkokusho; the combined format from the Reiwa 7 year onward) — a single form declaring the basic deduction, spouse deduction, 特定親族特別控除 (tokutei shinzoku tokubetsu kōjo, special deduction for specified relatives), 所得金額調整控除 (shotoku kingaku chōsei kōjo, income amount adjustment deduction), and more.
Currency note: the year-specific details in this article (the 定額減税 (teigaku genzei, flat-amount tax cut) has ended; the 「特定親族特別控除」 is newly created for the Reiwa 7 year and merged into the combined format, etc.) use the Reiwa 7 (2025) year as the example — the 特定親族特別控除 targets those with dependent relatives in a certain age range, with the covered persons and amounts per the National Tax Agency. The nenmatsu chōsei rules can change every year (for example, further changes are coming for the Reiwa 8 year / end of 2026), so for any given year's form names, fields, and deduction rules, follow what the National Tax Agency publishes for that year (see the nenmatsu chōsei portal link above) and the actual forms you receive that year.
Your company runs the settlement based on these declaration forms, and the result appears on the 源泉徴収票 (withholding tax statement) issued at year-end.
Common fields on the forms
- 扶養親族 (fuyō shinzoku) — dependent relatives (determines the dependent deduction).
- 配偶者の合計所得金額 (haigūsha no gōkei shotoku kingaku) — your spouse's total income (determines the spouse deduction).
- 保険料控除 (hokenryō kōjo) — deductions for various insurance premiums (life/medical/social insurance, etc.).
- 基礎控除 (kiso kōjo) — the basic deduction, applying broadly to taxpayers whose income is within a certain range.
- 給与所得控除 (kyūyo shotoku kōjo) — the employment income deduction, taken off salary income first.
- 特定親族特別控除 (tokutei shinzoku tokubetsu kōjo) — a deduction newly created in Reiwa 7 (for those with dependent relatives in a certain age range; covered persons and amounts per official sources).
- 源泉徴収税額 (gensen chōshū zeigaku) — income tax already withheld.
What you need to do
- When you receive the 申告書 (declaration forms) from your company, fill them in accurately as instructed (dependents, spouse, insurance premiums, home loan, etc.).
- Prepare and attach the supporting documents, e.g. the 保険料控除証明書 (hokenryō kōjo shōmeisho, insurance premium deduction certificate) and, from the second year onward, the home loan deduction certificates — original/copy requirements per your company.
- Return them by your company's deadline (companies usually set it around November–December; follow your own company's notice).
- At year-end / early the next year, check the 源泉徴収票 you receive and confirm the refund-or-collect result.
- If you fall under a case that requires filing your own return (see below), prepare a 確定申告 separately.
Possible deadlines / where the amounts are
- Deadline: the submission deadline for nenmatsu chōsei is set by your company (mostly before year-end); it is not a uniform National Tax Agency date — follow your company's notice. If you also need to file a 確定申告, that has a filing period set by the National Tax Agency; follow official sources.
- Amounts: after the settlement, see 「支払金額」 (shiharai kingaku) on the 源泉徴収票 for your annual income, and 「源泉徴収税額」 for your final income tax. For the specific deduction amounts (the basic deduction, employment income deduction, caps on the various deductions, and other figures), follow the National Tax Agency's explanations for that year.
On the difference from 確定申告: nenmatsu chōsei is handled by your company on your behalf and covers most employees; kakutei shinkoku is you filing with the tax office yourself. The two are not either-or — most people are done once nenmatsu chōsei is complete, but the following cases usually still require your own 確定申告:
- You want to claim the 医療費控除 (medical expense deduction) — nenmatsu chōsei cannot handle it.
- You have side-job/part-time or other non-salary income reaching the filing threshold.
- The first year of the home loan deduction (住宅借入金等特別控除, jūtaku kariirekin tō tokubetsu kōjo; from the second year onward it can generally be handled in nenmatsu chōsei).
- Cases such as salary income above a certain amount, or receiving salary from two or more places.
Whether you actually need to file a return, and the various threshold amounts, are per the National Tax Agency and your local tax office.
Which official body to check with when unsure
Filling in the declaration forms, the deadline, and carrying out nenmatsu chōsei are handled by your company; for the rules of the system, whether you need a 確定申告, and each deduction's amounts and conditions, rely on the National Tax Agency (国税庁, Kokuzei-chō) and your local tax office (税務署, zeimusho). Official explanations take precedence over any third-party interpretation. When needed, see the National Tax Agency pages listed at the end of this article, or bring your documents to the tax office and ask.
Common Japanese terms
- 年末調整 (nenmatsu chōsei) — year-end adjustment (your company settles your income tax at year-end)
- 確定申告 (kakutei shinkoku) — final tax return (filed yourself with the tax office)
- 源泉徴収 (gensen chōshū) — withholding of income tax (from salary)
- 源泉徴収票 (gensen chōshū-hyō) — withholding tax statement
- 申告書 (shinkokusho) — declaration form
- 扶養控除 (fuyō kōjo) — dependent deduction
- 配偶者控除 (haigūsha kōjo) — spouse deduction
- 保険料控除 (hokenryō kōjo) — insurance premium deduction
- 基礎控除 (kiso kōjo) — basic deduction
- 給与所得控除 (kyūyo shotoku kōjo) — employment income deduction
- 医療費控除 (iryōhi kōjo) — medical expense deduction